"Superfly" - submini tube version of Doug H's Firefly

[frequencycentral]

You can get higher voltage out of the SMPS by reducing the value of R8 (470R on my layout) or increasing the value of R10 (220k on my layout). But be VERY CAREFUL, it's possible to get insanely high voltages that will look great on your DMM for a few minutes/seconds until the whole thing melts....... I'd recommend making only very small changes, see what happens, then make another very small change until you get what you want.

[Perrow]

You can get higher voltage out of the SMPS by reducing the value of R8 (470R on my layout) or increasing the value of R10 (220k on my layout). But be VERY CAREFUL, it's possible to get insanely high voltages that will look great on your DMM for a few minutes/seconds until the whole thing melts....... I'd recommend making only very small changes, see what happens, then make another very small change until you get what you want.

I thought about that approach, maybe "inject" another trimmer to test, but I've also tried with a CMOS55 that doesn't look like it bothers about the "adjustable part" and only got about 150V. I'll give it a shot but I'll likely try new inductors as well (and double, or is that quadruple, check that I've got the UF4004 where it's supposed to be).

I've tried inductors pulled from computer power supplies but haven't really gotten any better results with them (unmarked so anyones guess what values they are), had to go by ear as to how much voltage I got as the DMM was all over the place with most of those inductors. Just thought today, while out walking, to test with my analog meter, perhaps it's not as easily confused.

I do have a standby switch mod. Short the connection between the collector and emitter of the transistor, the 555 stops, and you get a B+ of 12V. Let the tubes heat up, break the connection and the 555 starts and you'll get your regular B+.

[frequencycentral]

I do have a standby switch mod. Short the connection between the collector and emitter of the transistor, the 555 stops, and you get a B+ of 12V. Let the tubes heat up, break the connection and the 555 starts and you'll get your regular B+.

Neat! I like it a lot!

[Perrow]

Neat! I like it a lot!

Yeah, it's quite simple

[iccaros]

Neat! I like it a lot!

Yeah, it's quite simple

Perrow, sound samples?

[Perrow]

Neat! I like it a lot!

Yeah, it's quite simple

Perrow, sound samples?

I've no speaker to speak of (pun intended), currently using a salvaged 2", maybe 3", speaker from a radio without any enclosure 

But there are sound samples on the first page IIRC. Also, as I've yet to "find" the voltage mine's not that loud.

[iq01221]

Hi! I've got lot of epoxi dipped picking coils inductors , I'll post photos tomorrow, I've never seen something like this before today...

[iccaros]

just wondering if anyone has tried the Russian version of subminies, the 6N17B-V has a MU of 88 for example. The pin out is different

[iccaros]

One more question about the transformer,
First in this low wattage situation, I do not believe that it matters, I do not think the tube will over dissipate, but curiosity is getting to me..   

but according to the US NAVY NEET'S training and I believe Merlin's stuff, and giving this is class A I believe, I could be wrong.
190V^2/1.1watts = 32818 ohms per 1/2 of the transformer..

so I am curious, since I have not built one of these yet, If we place a 1ohm resistor on the cathode of the output tubes, we could read voltage across which would give us a 1 for 1 relationship to the current being drawn. or can someone measure the voltage off the cathode resistor (the 440 ohm) and it should be voltage/resistance = current.

[defaced]

Current at the cathode is composed of both screen and plate current.  Some reading in the data sheets or assumptions can be made to estimate the screen current.  But yes, measuring the voltage drop across a cathode resistor is a way to calculate cathode current.  This is standard practice in biasing tubes. 

[iccaros]

Current at the cathode is composed of both screen and plate current.  Some reading in the data sheets or assumptions can be made to estimate the screen current.  But yes, measuring the voltage drop across a cathode resistor is a way to calculate cathode current.  This is standard practice in biasing tubes.  

sorry for the misunderstanding, I am asking if someone who built this would measure this for me so I would have a better Ideal on how this is reacting to the 125A (2 & 5)8k load @ 8ohms, or did I miss something changing the pin out to the 22K taps in a post?
the optimum for the tubes would be 33K or am I wrong on that?

I am in the middle of sourcing parts for this, so this is all in the name of research.

[iccaros]

bump

[iccaros]

I noticed that too, but as this is virtually a straight copy of Doug H's Firefly I stuck to the Firefly schematic. I *suspect* the ohmage figure on the Firefly schematic refers to the maximum available from that transformer as opposed to the taps used. Maybe Doug could shed some light on it? The plate resistance of a 12AU7 is 6500 - 7700 ohms, so 8200 is pretty close. The plate resistance of a 6111WA is 4000 - 5000 ohm. So maybe there's a slighly better combination available. I did try different combinations including 2 and 4, with little difference THB. I'm currently building a Superfly with the addition of a tonestack and a master volume.  

Sorry to boost this
but new question along with my old..

for the inducter does this look good?
http://www.mouser.com/ProductDetail/API-Delevan/DC780-104K/?qs=sGAEpiMZZMsg%252by3WlYCkU45muCuneYXkPP0ToNV1U6o%3d

I was hoping that Dough or RG, PRR, Merlin would have an answer, the Firefly is using the 22K taps, This limits the current draw to 10% under the rated max for the 12au7, or at least close enough. I have always been told that output Independence should be about 10X your plate resistance, or somewhere in there. In this case it may not matter, as the SMPS may limit enough, or the tubes can handle more current than rated. Rick has had success so I know it works this way.

6111 ratings withe a 190v SMPS
190V^2/1.1watts = 32818 ohms

Firefly (12au7)  with 265 B+
265^2 / 2.2 watts = 25536

[iccaros]

@ Dan: Well they look right physically, but the ones I use are labelled '104'. I think inductor labelling is the same as cap labelling, so (to me at least, I'm happy to be corrected), the '101' markings don't look right.

@ Hides: I'm using 15mm nylon standoffs from Banzai.

in this case 101 = 100uh and 104  = 100000 uh, the first two numbers like capacitors, the last number is how many zeros to add. Unlike capacitors we do not move the decimal over 5 spaces.
http://how-to.wikia.com/wiki/How_to_identify_inductor_markings

[misterg]

Current at the cathode is composed of both screen and plate current.  Some reading in the data sheets or assumptions can be made to estimate the screen current.  But yes, measuring the voltage drop across a cathode resistor is a way to calculate cathode current.  This is standard practice in biasing tubes.  

sorry for the misunderstanding, I am asking if someone who built this would measure this for me so I would have a better Ideal on how this is reacting to the 125A (2 & 5)8k load @ 8ohms, or did I miss something changing the pin out to the 22K taps in a post?
the optimum for the tubes would be 33K or am I wrong on that?

I am in the middle of sourcing parts for this, so this is all in the name of research.

See reply #199 (mine) - somewhere around page 10.

Use 20k + for this circuit.

Andy

[iccaros]

Thanks, so did you use the 15K from the transformer you posted? I am in the states, so I could not find it here, but @ 9 pounds that is what $24 plush shipping and the hammond is only $34 here

[Scruffie]

Not to derail this thread/line of conversation but has anyone taken a stab at my full sized tube layout yet?

Only i'm a Transformer, PCB, Inductor, MOSFET & High Wattage Resistor away from being able to finish it...

Taylor?

[Taylor]

Haven't had time I'm afraid. I ended up grabbing a Valve Jr. I am very curious about how it turns out though. Sorry! 

[iccaros]

Not to derail this thread/line of conversation but has anyone taken a stab at my full sized tube layout yet?

Only i'm a Transformer, PCB, Inductor, MOSFET & High Wattage Resistor away from being able to finish it...

Taylor?

you mean running off of SMTP or just using standard tubes, as the values are a basic firefly, its the supply and the subminis that make this interesting.

Once I have the power supply working I may do a test, I am also building a High Octane with sub mini tubes so I want to test that also..

[Scruffie]

Haven't had time I'm afraid. I ended up grabbing a Valve Jr. I am very curious about how it turns out though. Sorry! 

Wait... you purchased an amp over DIY?



  No Worries.

Not to derail this thread/line of conversation but has anyone taken a stab at my full sized tube layout yet?

Only i'm a Transformer, PCB, Inductor, MOSFET & High Wattage Resistor away from being able to finish it...

Taylor?

you mean running off of SMTP or just using standard tubes, as the values are a basic firefly, its the supply and the subminis that make this interesting.

Once I have the power supply working I may do a test, I am also building a High Octane with sub mini tubes so I want to test that also..

I mean the PCB layout I made several pages back, using an MAX1771 Charge Pump with Onboard Pots & a 12AU7 & AX7 to fit a 1590BB.